The field of art to which the present invention pertains includes a focus detecting system capable of computing the object distance.
The prior art to which the present invention is directed includes the focus detecting system of the type capable of detecting the object distance by comparing the image patterns obtained through two separate light passages through electrically processing the signal obtained by receiving light through two separate light passages on a pair of groups of light responsive elements provided adjacently with each other on a wafer of semiconductor.
The conventional focus detecting system of this type requires a complicated optical structure for guiding light through two separate light passages to two separate groups of light responsive elements provided adjacently with each other on a face of a wafer of semiconductor. Furthermore, the wafer of semiconductor composing a unit of light responsive elements is costly when two separate groups of light responsive elements are required. Still further, the accuracy of the conventional system of this type in focus detection is not satisfactory because the difference in the sensitivity between the groups of light responsive elements or the difference in the amplification of the amplifiers affects the accuracy disadvantageously as the image patterns obtained through two separate light passages are compared with each other by means of two sets of groups of light responsive elements.